WordPress Post Template Link Cover

wp-post-template-link-cover.php

<?php
/**
 * Block Style For covering post template blocks with clickable link.
 */

add_action( 'init', function () {
	register_block_style(
		'core/post-title',
		[
			'name' => 'link-cover',
			'label' => 'Link Cover',
			'inline_style' => <<<CSS
				.wp-block-post:has(.is-style-link-cover) {
					position: relative;
					anchor-name: var(--anchor-name, --post);
				}

				.wp-block-post:has(.is-style-link-cover) a[href] {
					position: relative;
					z-index: 2;
				}

				.wp-block-post .is-style-link-cover > a[href] {
					position: static;
				}

				.wp-block-post-title.is-style-link-cover > a[href]::after {
					content: "";
					position: fixed;
					position-anchor: var(--anchor-name, --post);
					z-index: 1;
					margin: 0;
					left: anchor( left );
					top: anchor( top );
					right: anchor( right );
					bottom: anchor( bottom );
				}
				CSS,
		]
	);
} );

/**
 * Inject CSS anchor names into post blocks.
 *
 * @param string $block_content The block HTML.
 * @return string
 */
add_filter( 'render_block_core/post-template', function ( string $block_content ) : string {
	static $template_instance = 1;

	$block_content = new WP_HTML_Tag_Processor( $block_content );

	while ( $block_content->next_tag( [ 'class_name' => 'wp-block-post' ] ) ) {
		$var_name = preg_replace( '/^.*?\s(post-\d+)\s.*?$/', '$1', $block_content->get_attribute( 'class' ) );
		$style = $block_content->get_attribute( 'style' );
		$block_content->set_attribute( 'style', $style . ';--anchor-name:--' . $var_name . '--' . $template_instance );
	}

	$template_instance++;

	return (string) $block_content;
}, 10, 1 );